Apparatus for roasting ore



INVENTOR C. A. Gad/a C. BY

Filed Aug. 13, 1934 C. A. GALLAGHER ET AL APPARATUS FOR ROASTING OREFeb. 9, 1937.

her M. Alfie/1 ATTORNEY Patented Feb. 9, 1937- PATENT OFFlCE- 2,010,53APPARATUS FOR ROASTING one Charles A. Gallagher and Carl M. Allen, 0511-fornia, Pasassignors to General Chemical Com- D y, New York, N. York Y.,a corporation of New t Application August 13, 1934, Serial No. 739,547 3Claims. (01. 263-21) This invention is directed to apparatus forroasting metallic sulfides, and more particularly for roasting finelydivided sulfide ores to desulfurize the same and to produce sulfurdioxide for use in the manufacture of sulfuric acid, or for any otherpurpose desired.

To a large extent, present practice in sulfide fines roasting includesuse of mechanically operated multiple hearth constructions, such, forexample, as the well known MacDougal, Herreshoff, and Wedge burners, andwhile such burners provide effective roasting, the complicatedconstruction and operation thereof involve considerable initial andmaintenance expense. To some .degree, roasting of sulfide fines while ingaseous suspension has more or less recently displaced the bed roastingoperations carried out in the above mentioned hearth burners.

Suspension roasting is best applicable when the fines are in arelatively finely divided state,

and this method presents the notable advantage A over the mechanicalmultiple hearth operation of considerably lowering the cost ofproduction, by reason of the elimination of the relatively complicatedand moving parts, expensive rabbling and other apparatus inherent in theconstruction and operation of such mechanical burners. In the practiceof suspension roasting, however. and particularly as applied to roastingmetallic sulfide fines, difiiculties are encountered which must beovercome before the theoretical advantages of this type of operation arepractically available. v

The invention is directed generally to improvements in burners forsuspension roasting of sulfide fines, and. moreespecially tofeedmechanisms for injecting the fines into burner combustion chambersand for forming therein a dispersion of the fines in gaseous suspension.It is one of the objects of the invention to provide flexible and easilyadjustable injector mechanisms so constructed as to permit feeding offines in the burner combustion chamber in such a way as to substantiallyprevent contact of fines with the heated inner walls of the combustion Ichamber to thus avoid accumulation on the walls of accretions or scar.formation, a well known difilcult'y encountered in suspension roasting.Another object of the invention is to provide feed mechanisms affording1mproved dispersion of fines over the cross-sectional area of thecombustion chamber. The invention additionally aims to provide feedinjectors including mechanisms by means of which the quantity of linesdrying hearth.

' ble arms framework l8, discharges from which fines are intermittentlydropped onto 21 rotating with shaft 23.. i

l3, by suitable brackets downwardly sloping passages or conduits fedinto the furnace may be accurately controlled and fluctuations of orefeed avoided.

The invention accordingly comprises the features of construction,combinations of elements,

and arrangement of parts, which will be exemplified in the constructionhereinafter set forth. The nature of the invention and the objects andadvantages thereof may be more fully understood from a consideration ofthe following description taken in connection with the accompanyingdrawing, in which Fig. l is a vertical section of a sulfide ore burnerfor use in connection with which the improved injectors of the inventionare particularly designed;

Fig. 2 is an enlarged view, partly in section and partly in elevation,showing one preferred form of the'improved injector;

' Fig. 3 is anelevation taken substantially on the line 3-3 of Fig. 2,and

Fig. 4 is a plan taken on the line L-l of Fig. 2.

Referring particularly to Fig; 1 of the drawing, numeral l0 designatesgenerally a shaft burner comprising a shell I I, constructed of suitablerefractory material such as firebrick, defining a roasting chamber l2 ofcylindrical crosssection. Surrounding shell H, is a steel casing l3acting as a protective reinforcement for the furnace. The upper end ofthe combustion chamber is closed off by a crown IS, the top side ofwhich forms a drying and preheating hearth ll. The cylindrical shelllland casing l3 project upwardly beyond the crown I5, and carrya steelframework l8 which in turn supports ore feeding and rabble mechanism forthe The 1 surface of hearth I1 is' slightly coneshaped and slopesdownwardly toward the shell of the burner. Lying above the hearth arerabl9- having downwardly projecting plows 20 pitched to work sulfidesgradually toward the circumference of the "drying hearth. Arms I9 arerotated by a motor 22 through shaft 23 supported in bearings so as tomaintain the lower ends of the plows 20 properly spaced with respect tothe'surface of the drying hearth ll. An ore bin 24, mounted on ore ontoa platform 25 approximately the center of hearth I1 by a sweepAttached'to steel shell not shown, are hoppers 30 covered by slopin'gscreens 3|. Cut in shell l l near the uppererid are v threaded throughthe upper part of sleeve'38 and provides means by which the verticalposition of feed regulator 36 may be adjusted. Welded or otherwiseattached to the lower end of sleeve 38 is a plate 48 having an opening42 in alignment with the axis of sleeve 38 and also having an ex-,tension 44 shown in plan in Fig. 4. Extension or bracket 44 is drilledtoaccommodate bolt 46 headed on the lower end and threaded on the upperend to receive winged nut 48. Adapted to rotate about bolt 46 onloosening of nut 48 is a circular plate 50 having openings H, 52, 53 and54 of progressively increasing size, orifice 54 being 'of about the samediameter as opening 42 inplate 40. These openings are spaced from thecenter of plate 58 so that each opening on rotation of the plate maybecome axially aligned with opening 42 in plate 48. It will be seen thatby loosening the clamp and rotating plate 50, the effective size of theopening in the bottom of feed regulator 36' may be changed to regulatethe capacity of the burner.

The adjustable injectors of -the invention, indicated generally byreference numeral 60, are each supported by a bracket 6| attached to thesteel shell I3. Referring particularly to Fig. 2, each injector.comprises a Y-fitting 63 the bottom of which is threaded to accommodatean externally threaded bushing 64 which slidably receives a gas jet 66.One branch of the Y-fitting is threaded as at 68 to provide forattachment to the fitting of the lower discharge end of the funnel I8adapted to be positioned directly beneath the feed regulator 36. Awinged bolt 12 passing through bushing 64 provides means for adjustingthe end of jet 66 with reference to the axis of funnel 18. The otherbranch of fitting 63 is threaded to receive one end of a metallic nozzleI3 which projects through an opening 14 in the furnace wall I I andprovides an ore inlet conduit 15 through which fines are injected intothe combustion chamber I2. A dispersing cone I6, positioned beneathorifice 42, is supported as indicated in the drawing byv three shortlegs engaging the inner surface of funnel I0.

Welded tothe upper end of bolt 11 (Figs. 2 and 3) is a trough-like plate18 to which nozzle 13 may be clamped by means of a U-bolt 88, the endsof which pass through'plate I8. Referring particularly to Fig. 3, thelower threaded end of bolt 11 is adapted to pass through an elongatedslot 8I in the horizontal leg 82 of an angle bracket 83. Slot 8| permitssidewise adjustment of nozzle 13. The vertical position of bolt 'I'Iwith reference to bracket 83 may be adjusted by set nut 84 and wingednut 85. The lower end of vertical leg 81 of bracket 83 is drilled toaccommodate a bolt 88 which may he slid back and forth in a horizontalslot 98 in bracket 6|. Bracket 83 is held tightly in any desiredposition with reference to bracket 6| by means of winged nut 92 threadedonto the end of bolt 88. From the foregoing, it will be seen the weightof fitting 63 and the as:

. 2,070,531 through which on: is passed from the drying sociated partsis supported by bracket 6| fixed to the furnace casing I3.

A bustle 95 having an inlet 96 provides for gas supply to injector jet66, the bustle 95 communicating with jet 66 through pipe 91 including acontrol valve 98, a pressure gauge 99 and a double universal jointindicated at I88.

The burner may be provided with any suitable number of injectors. In theillustrated embodiments of the invention, the two injectors shown inFig. 1 are diametrically opposed. In some instances it is desirable toemploy say three or more injectors equally spaced about thecircumference of the burner. It will be understood where three or moreinjectors are included in the furnace con-.

struc'tion, a hopper 30 and a feed mechanism 36 are provided for feedingore thereto.

oxidizing gas to support the roasting operation is introduced into thechamber I2 through 'circumferentially spaced ports -I 82, positionedadjacent the ore injectors, and connected through short pipe sections,not-shown, with a bustle I03,

communicating with an air inlet connection I04,

open to the atmosphere and having a control valve I05. g

The-bottom of the combustion chamber I2 is formed by a hopper-shapedbrick-faced hearth I81 terminating in an outlet I88 through whicn cindermay be continuously discharged into -a conveyor. A gas main I I0,opening into the combustionchamber, just beneath the crown I5, isconnected to the suction side of a fan which effects withdrawal ofgaseous combustion products from the burner.

The apparatus of the invention may be employed in connection with theroasting of finely divided metal sulfidessuch as iron pyrites,pyrrhotite, zinc sulfide or ar senopyrite. The adaptability andoperating advantages of the improved apparatus may be more clearlyunderstood from the following in which the apparatus is described inconnection with the roasting of iron pyrites.

A supply of sulfide fines is maintained in'the bin 24 by suitableconveyor or elevator mechanism, not shown. Before roasting is begun,combustion chamber I2 is preheated to temperatures above the ignitionpoint of the particular.

' heat is obtained in' the combustion chamber, the

motor 22 is started, and rabble arms I9 and sweep 2! may be rotated at arate of, say, one revolution in two minutes. Fines run continuously outof the bin 24 onto platform 25, and on each revolution of shaft 23 aregulated quantity of fines is swept off the platform to approximatelythe center of hearth I'I.

During rotation of the rabble arms I9, the concentrates are graduallyworked across the heated surface of hearth I! and into'passage 34. Thedry or partly dry ore runs onto sloping screens 3|, which remove lumps,and then into hopper 30. The finely divided particles drop through pipe35 into cylindrical sleeve 38 of feed.

variable size, and in accordance with the fineness of the ore, the sizeof the combustion chamber, the desired capacity of the burner, and othervariable operating conditions, the plate 50 may be positioned byadjustment of nut 48, so as to place an orifice of the desired sizebeneath the opening 42 in the bottom ofsleeve 38. As will be hereinafterobserved, the vertical position of funnel l may vary, and to provide forthis, the position of feed regulator 35, with respect to pipe 35, may beregulated by adjustment of winged bolt 39 to insure discharge of finesinto the funnel. The plate thus provides a fixed opening for accuratefeed control preventing fluctuation in ore supply which may readily takeplace with other types of adjustable valves.

The fines accordingly flow steadily from regulator 36 into funnel l0,which conveys the ore stream directly and preferably without anydecrease in velocity of the particles into Y-fittin'g 63 in which thefines are swept up by the air introduced through jet 66 and carriedthrough pipe 13 into the combustion chamber. Conical surface 16 infunnel serves to divide the stream of ore falling from the orifice inplate 50. The inner end of jet 66 is preferably located inwardly of theaxis of funnel 10 so that the fiow of air from the jet induces a slightminus pressure in the vertical leg of Y 63 and results in an actualsuction drawing in air and ore through funnel Ill. Orifice plate 50regulates the flow of ore to the feed nozzle and does not permit ore tobuild up in the funnel. In operation, ore and air are sucked in thethroat of funnel 1!), become more or less uniformly dispersed by conesurface 76, pass through Y 63 and are given an additional impulse onpassing the end of jet 66, resulting in a very homogeneous dispersion ofthe finely divided ore in air at the outlet of the feed nozzle.

Streaky or fluctuating feed is avoided, roasting of the ore is morecomplete and gas strength is more easily kept uniform by operating inthis manner.

To effectively carry out the roasting process, the manner of introducingthe fines into the combustion chamber is of major importance. The

fines should be fed into the chamber so that each particle is suspendedin the roasting atmosphere for a maximum period of time, and also sothat contact of the fines with the walls of the combustion chamber issubstantially avoided. To this end, by means of the feed mechanism ofthe present invention, the horizontal and vertical angles of the axes ofnozzles 13, theamount of fines fed into the injectors from pipes 35, andthe air pressure in jets 66, adjusted by valves 98, 'may be convenientlyregulated with respect to the particular size of the roasting chamber sothat the ore particles from each injector rise through the combustionchamber, away from the walls thereof, to an elevation justbelow theunderside of crown l5. The horizontal and vertical angular position ofnozzles 13 and the rate I ber may be obtained, and contact between anysubstantial quantities of ore particles and the hot Walls of theroasting chamber is prevented, thus avoiding accumulation of scar on thewalls.

In Fig. 1, the dotted line H5 indicates the approximate path of travelof an ore particle of average size introduced through the injector onthe left side of the burner.

From the previous description, it will be understood nozzle l3 and theY-fitting B3 are rigidly connected to the upper end of bolt Tl. Byloosening the winged nut 92, the vertical angle between the axis of thenozzle and the horizontal may be adjusted, thus permitting swinging ofthe nozzle through an are lying in a vertical plane and extendinglongitudinally of and disposed at a right angle with the burner wall.loosening nut 92, by means of the horizontal slot 90, movement of theinjector back and forth relative to the wall of the burner may beeffected. Nozzle l3 and the Y-fitting may be moved bodily up or downbymoving set nut 85 and winged nut 85 to permit vertical movement of boltl1 through the, horizontal section 82 of bracket 83. Also by means ofslot ill the nozzle may be adjusted sidewise.

Under some operating conditions, there may be instances Where it .is'desired to introduce the fines into the roasting chamber in a directionother than radially. It will also be understood that by loosening setnut 85 and winged nut 85, the injector may be moved through a horizontalangle about bolt Tl as an axis. By means of this adjustment fines may beinjected into the combustion chamber radially or in a direction oil agiven radius. To permit the desired movement of nozzle 13, opening 14 inthe furnace Wall II is made large enough so that angle A (Fig. 2) mayvary for example between 15 and 45 degrees, and so that nozzle 13 may beswung horizontally through an arc of say 45 degrees. a

The major portion of the total quantity of air, or other oxidizing gas,necessary to support roasting is drawn into the combustion chamber atthe bottom thereof from bustle I03 through ports I02. Where air isemployed for injecting the fines through the nozzles, not more thanabout 10% of the total air required for oxidation would ordinarily beintroduced through air jets 66, although larger amounts may be used ifdesired. The position of the ends of jets 56 with respect to the axes offunnels I! may be adjusted by manipulation of tail nut 12, and ifnecessary bushings 64 and jets 66 may be removed from fittings 63 topermit cleaning; of the latter or of the nozzles 13.

' By suitable adjustment of the injectors, a relativcly uniformdistribution of partially roasted particles is formed over the majorportion of the upper end of the combustion zone. The particlesthereafter drop to the bottom of the combustion chamber. The blower ingas line H0 is operated so as to draw sufficient air into the combustionchamber to supply enough oxygen to effect substantially completeoxidation of the fines, and also so that the velocity of the risingstream of air through the combustion chamber is not sufiicient tointerfere with the free gravity fall of the fines. Becauseof theadjustable features of the injectors, a satisfactory dispersion of oreparticles over a major portion of the top of the combustion chamberisobtained, and ore particles'during'the upward movement are not thrownagainst the walls of the roasting chamber, thus avoiding contact offines with the hot walls of the combustion chamber when the fines are ina state conducive to scarring. As the downward flow of the fines is insubstantially Also, by

'straight lines or at a high angle, subsequent coni tact of fines withthe walls of the combustion chamber is avoided, thus further preventingconditions under which scarring might take place, the iron oxidecinder-falling on hoppershaped hearth 101 runs through opening I08 intoa suitable conveyor.

We claim:

1. The combination with a reaction chamber having an opening in a wallthereof, of means for feeding into said reaction chamber finely dividedmaterial in dispersed condition, said means comprising a movableinjector having a material inlet passage open to the atmosphere and anozzle disposed in angular relation with respect to the inlet passageand extending through said opening, means in said injector inlet passagefor dispersing in atmospheric air material fed into said injector inletpassage, a feed regulator for feeding material into the injector and forcontrolling such feed so as to prevent stopping up of said inlet passageto flow of atmospheric air, means for changing the position of the feedregulator to accommodate changes of position of the injector materialinlet passage, means including an air jet in said nozzle for inducing inthe inlet passage a minus pressure to form in and draw through the inletpassage preliminary dispersion of material in air and for introducinginto the preliminary dispersion an additional stream of air underpositive pressure to cause the material to flow through the nozzle andform at the outlet thereof a relati ely homogeneous dispersion ofmaterial in air, means for swinging the nozzle.

through an are lying in a plane extendinglongitudinally of and disposedat a right angle with the wall, means for swinging the nozzle through anare lying in a plane at a right angle with said first mentioned planeand means for holding the nozzle in a fixed position in each of saidarcs.

2. The combination with a reaction chamber having an "opening in a wallthereof, of means for feeding into said reaction chamber finely dividedmaterial in dispersed condition, said means comprising a movableinjector having a material inlet passage open to the atmosphere and anozzle disposed in angular relation with respect to the inlet passageand extending through said opening, a cone in said injector inletpassage arranged to disperse in atmospheric air material fed into saidinjector inlet passage, a feed regulator for feeding material onto saidcone and for controlling such feed so as to prevent stopping up of saidinlet passage to flow of atmospheric air, means for changing theposition of the feed regulator to accommodate changes of position of theinjector material inlet passage, means including an air jet in saidnozzle for inducing in the inlet passage a minus pressure to form in anddraw through the inlet passage preliminary dispersion of material in airand for introducing into the preliminary dispersion an additional streamof air under positive pressure to cause the material to flow through thenozzle and form at the outlet thereof a relatively homogeneousdispersion of material in air, means for universally changing theposition of the injector nozzle in the wall opening, and means forholding the nozzle in a fixed position.

3. The combination with a reaction chamber having an opening in a wallthereof, of means for feeding into said reaction chamber finely dividedmaterial in dispersed condition, said means comprising a movableinjector having a material inlet passage open to the atmosphere and anozzle disposed in angular relation with respect to the inlet passageand extending through said opening, a cone in said injector inletpassage'arranged to disperse in atmospheric air material fed into saidinjector inlet passage, a feed regulator for feeding material onto saidcone and for controlling such feed so as to prevent stopping up of saidinlet passage to flow of atmospheric air, means for changing theposition of the feed regulator to accommodate changes of position of theinjector material inlet passage, an air jet in the injector in alignmentwith said nozzle and having the end thereof positioned inwardly of theaxis of the. material inlet passage and arranged to induce in the inletpassage a minus pressure to form in and draw through the inlet passagepreliminary dispersion of material in air and to introduce into thepreliminary dispersion an additional stream of air under positivepressure to cause the material to flow through the nozzle and form atthe outlet thereof a relatively homogeneous dispersion of material inair, means for universally changing the position of the injector nozzlein the wall opening, means for holding the nozzle in a fixed position,means for moving the injector bodily toward and away from said opening,and means for moving the injector longitudinally with respect to saidwall.

CHARLES A. GALLAGHER. CARL M. ALLEN.

